1. Field of the Invention
This invention is related to a single-package aqueous polymeric formulation that contains a polymeric ingredient having a latex seed core and both acid functional and pendant moieties having the ability to form stable enamine structures by reaction with amines, e.g., acetoacetoxy functional pendant moieties. The invention is also directed to a process for preparing such aqueous polymeric formulations. The formulations of this invention are highly useful in protective coating compositions having ambient cure capability, e.g. wood, metal and concrete coatings.
2. Related Background Art
Ethylenically-unsaturated monomers containing active methylene groups such as ##STR2## and polymers prepared from such monomers having pendant active methylene groups have long been known. For example, U.S. Pat. No. 3,459,708 discloses acetoacetates, such as 2-acetoacetoxyethyl methacrylate and 2-acetoacetoxyethyl acrylate, for forming polymers to be used as gelatin extenders or substitutes in photographic films.
The preparation of various acetoacetates and acetoacetamides is well known. For example, S. J. Witzeman, et al., The Journal of Organic Chemistry, 56, 1713-18 (1991) discloses the preparation of acetoacetates and acetoacetamides by reaction of various nucleophiles with tert-butyl acetoacetates. This reference reports that acetoacetylated materials may be used as chemical intermediates in the pharmaceutical, agrichemical, chemical and polymer industries.
More particularly, it is known to use acetoacetoxy-functional moiety-containing polymers in combination with polyfunctional amines in latex compositions. Such compositions may be applied to substrates to form films by crosslinking the amines with the acetoacetoxy-functional moiety through the formation of enamine linkages. For example, U.S. Pat. No. 5,498,659 discloses a particularly advantageous storage-stable single-package latex formulation containing a polymeric ingredient having at least pendant moieties having the ability to form stable enamine structures by reaction with amines, e.g., acetoacetoxy functional pendant moieties. This reference discloses that preferred acetoacetoxy functional moiety-containing ingredients include acetoacetamide methacrylate and acetoacetamide acrylate, acetoacetoxyethyl methacrylate ("AAEM"), acetoacetoxyethyl acrylate ("AAEA"), allyl acetoacetate and vinyl acetoacetate. While the acetoacetoxy functional moiety-containing ingredients disclosed in U.S. Pat. No. 5,498,659 may be used to provide desirable latex formulations, it has been found that the production of such formulations on a large scale is difficult.
Copending U.S. applicantion Ser. No. 08/518,941, filed Aug. 24, 1995, teaches ethylenically unsaturated 1,3-diketoamide functional compounds, polymers and latex formulations containing the same. Latexes made utilizing such unsaturated functional compounds possess improved hydrolytic stability.
The use of latex seeds in polymerization reactions to obtain latex polymers having uniform particle size is disclosed, for example, in U.S. Pat. No. 5,189,107, U.S. Pat. No. 4,122,136 and U.S. Pat. No. 3,687,923. Copending U.S. Pat. application Ser. No. 08/539,808, filed Oct. 5, 1995, describes the use of latex seeds in combination with the generation of a gradient polymeric morphology by varying the concentration ratio of the monomer feeds. None of these references disclose or suggest that novel single-package aqueous polymeric formulations could be prepared effectively on a large scale through the use of latex seed technology.
A high quality latex formulation including pendant moieties having the ability to form stable enamine structures by reaction with amines, e.g., acetoacetoxy functional pendent moieties, that can readily be prepared in an effective large scale manner will advantageously provide significant commercial advantage ever prior art formulations.